Insanity
by Double M B
Summary: Mutagen get's all over Donnie and does some weird stuff with his head. (Rated T for some reason?) (Cover by me)
1. Chapter 1

Donnie's POV

Mutagen dripped down my face and I tried my best not to yell out. My eyes were shut tight and I was on my knees. My heart beat like a drum and my body shook. I was scared. I mean, who wouldn't be? I could turn into some kind of ugly creature just because of my mistake. Why was I so stupid? I'm supposed to be the smart one, right? Well, apparently not at that moment.

I felt the mutagen seep into my head. _Crap, it's going for my brain._ I thought, trying to shake it off. _Please, turn me into a hideous creature, just don't hurt my mind!_ I pleaded, tears falling down my face from the pain. I opened my eyes to see Leo and Raph holding Mikey back. Everything was like a movie. It didn't really feel like I was actually here. I noticed that Mikey's movements were in slow-mo. What is this stuff doing to me?!

"H-help." I said weakly, reaching out for my brothers. their movements sped up and they back away quickly.

"DONNIE!" Mikey yelled, tears streaming down his face. I fell to my hands and knees, my arms shakey and about to give out on me.

I started crying for real. Crying in fear. Confusion. Agony.

Everything started fading, "L-leo," I cried pitifully. Leo looked over at me and turned away.

"Don't die Donnie." Raph said, fighting tears (I could tell). Mikey collasped and started sobbing loudly. Leo sniffled and turned his whole body in the other direction. How could they just stand there and watch me?!

I started getting dizzy and my arms gave out, making me fall on my face on the hard ground.

"Donnie, stay with us." Raph said, walking over but still keeping his distance. I rolled over, my eyes drifted shut and causing Raph to yell something at me. It sounded like he was yelling through a pillow. There was a sudden sharp pang in my head and I yelled out, clutching my head. I started shaking from the pain. It got colder all of a sudden. I turned my head side-to side, wrinching in pain.

_This is your fault Don._ I head a voice say I grit my teeth. _It's your fault the mutagen fell on you_. Tha voice said. I screamed. _You deserve this pain, _"SHUT UP!" I cried, trying to breathe. Tha pain intensified and I started crying/yelling, my eyes shut tight as I kicked and flailed my arms and legs.

_You should just die and get this over with. _The voice said. I kept my eyes shut tight. Whoever was talking to me needed to shut the heck up. My breathing got uneven and it got hard to breath. I started coughing and gripped my plastron.

_Stupid, stupid Don_. "GO AWAY!" I cried, trying to get a breath. I heard Leo yelling at me and tried opening my eyes.

_You're brothers are about to abandon you, you know. _The voice said, _You should just keep your eyes shut_. I screamed and yelled some more. I caught the slightest glimpse of Mikey crying and Raph pacing around. Leo stood over me, just, staring.

"H-help," I begged, coughing and turning to my side. My breathing got quick and my heart rate rose. I closed my eyes back and grit my teeth, opening my mouth to scream but no sound to be heard. My breath was got more uneven with every breath I took and my body started shaking. I hugged myself and took my last breath...

...before everything faded away.

Leo's POV

"Donnie!" I yelled, wanting to shake him awake, but afraid to touch him. Mutagen somehow gravitated to his head and soaked in. I staggered back, "D-donnie?" I asked quietly. Mikey bent down on his knees a few feet away from Don and sobbed loudly.

"B-b-bro," Mikey said between sobs. Raph kept pacing, practicly making a trench in the concrete floor. I took deep breaths, trying to stay calm.

"R-Raph!" I called. Raph stopped and looked up. I noticed faint tear marks on his dirty mask, "Help me carry him to the lair."

"We can't Leo." Raph replied with a stern look.

"Yes we can, now help me." I said, stepping towards my little brother.

"Leo, he's been drenched in mutagen. He's gonna go crazy on us when he wakes up." Raph yelled, yanking me back.

"No he's not Raph." I said, giving him a determined look, "He's out brother, he'd never hurt us." I said, trying to convince myself.

"What about Timothy?" Raph responded. I shook off his hand and stared at the ground.

"L-leo," Mikey asked, his voice quiet, "w-will Donnie be okay?" He begged, a new batch of tears running down his face.

"Mikey," I started, taking a step towards him. Mikey turned away and started crying. I took a deep breath and turned back to Raph, "We're stayig the night here. Or, at least I am." I said. Raph stared at me like I was crazy, "I'm not leaving my brother."

"Fine. But we should chain him up in case he, you know, freaks out like Leatherhead." Raph suggested. I sighed. It was probably the best thing to do.

"Okay." I said in almost a whisper, "Where's a chain?"

**I'm sorry I've been starting a bunch of new fanfictions, I just have too many ideas and I have to get them out!**

**Please review!**


	2. Chapter 2

Donnie's POV

"Leo?" I asked, opening my eyes a bit. I looked around groggily; handcuffs were on my wrists and connected with a chain on the wall behind me. This was my room. How'd I get here?

_Finally, you're awake_. The voice said. I groaned.

"Who are you?" I asked, trying to sit up a little. I looked around the room to find no-one around, "Where are you?"

_You're so stupid Don. Geez_. It said, I started yanking at the chains.

"Show yourself!" I yelled.

"Donnie?" A voice came.

"Who the hell are you?!" I demanded, yanking at the chains. Someone peeked in from the door.

"D-donnie?" Raph asked, stepping in.

"Sorry Raph." I said, looking down.

"Y-you okay?" He asked, sitting a tray of coffee and some toast on my nightstand. I nodded a little.

"My head hurts a little, but other than that, I'm fine." I said with a shrug. I was about to mention the thing about how I was hearing a voice , but decided against it.

_Why don't you mention me, Donatello? _The voice said, as if on cue. I groaned a little and rubbed my head. Raph gave me a weird look then picked up the tray.

"Anyway, here's some breakfast, just call if you need anything." He said, standing up and handing it to me. I smiled up at him.

"Thanks." I said. He nodded and left the room.

_You shouldn't thank him! He was about to abandon you!_ The voice yelled. I grit my teeth.

"Shut up." I said, trying not to raise my voice. I picked up the mug of warm coffee and took a sip.

_He just wanted to get away to protect himself. He's just happy you're alive so you can make stuff for the team._ It said. I slammed the mug back down on the tray.

"He thought that I'd go all nuts!...Which, I kinda am!" I yelled, looking around the room, "Now, show yourself!" I heard something from the dark corner in my room and squinted.

_Hello, Donatello_. It said. He stepped forward and I say it was...

...me.

"Who-? What-?" I asked, looking at him. He gave an evil smile.

_Don't think too hard about it, you'll hurt yourself_. He said, putting his hands behind his back and walking over.

"You can't be real though. It's not possible." I said, perplexed.

_Oh, but I am very real._ He said, raising a hand and slapping me across the face.

"I-I felt that," I mumbled, holding my hand to my cheek. It stung bad, "H-how?!"

_You ask to many questions. You want me to smack you again?_ He asked.

"Wait, you didn't slap me, it was the power of suggestion." I said, trying to organize my thoughts. He rolled his eyes and punched me in the gut. I grunted and hunched over.

"Stop!" I demanded, not looking up at him.

_No._ He said, slapping me again. I grit my teeth and reached for the coffee mug.

"STOP!" I yelled, throwing the mug in his direction. He dodged and it slammed against the wall behind him, making it shatter to pieces, "You're not real. You can't hurt me."

_Oh really? Then, what's this?_ He asked, twisting my arm in an impossible position. I screamed in pain and he released me.

"L-leo!" I called, hunched over, "I-I need you!"

_Pfft. You wimp._ Don said, disappearing.

"Yeah Donnie?" Leo asked, poking his head in. At first I was about to start yelling, but seeing it was Leo and not, well, me, I didn't.

"C-can you stay in here with me?" I asked, taking deep breaths.

"How-How'd you get those bruises?" Leo asked, alarmed. I looked up at him shyly.

"Um," I started, not knowing what to say. He shrugged and looked around the room.

"What happened to the mug?" He asked, nodding to the spilt coffee and the shattered clay.

"I threw it." I answered without thinking. Leo gave me a confused and shocked look and I turned away. I fake coughed, "Can-can you just let me out of these barbaric chains?" I asked with a weak smile.

"Um, not yet Don. Sorry." He said, stepping away.

"Please don't leave!" I begged, pulling at the chains.

"D-Don, I'm gonna get Splinter." He said, reaching for the door. I yanked as hard as I could.

"L-leo," I pleaded, "_please_." Leo stared at me in alarm. I bit my lip.

"Splinter!" Leo called, not moving an inch. I took a deep breath.

"Thanks." I said, relaxing.

_Just because he's here doesn't mean I'm gonna leave. _Don taunted.

"Shut up." I muttered, looking around the room a little. Leo stared at me. I knew he was probably freaked out, I was too.

"Yes?" Splinter asked, entering the room, "I'm glad you're awake Donatello." He said, nodding to me. I smiled a bit.

"Hello sensei." I said, sitting up.

"Are you feeling alright?" He asked, walking over and sitting down on the bed.

"Yes, can you please bring in my laptop and some needles please? I need to figure out what's wrong with me with a blood sample." I said. Leo and sensei exchanged a look.

"We can get the laptop, not the needles." Splinter answered.

"I need to figure out what's wrong!" I said, louder than I wanted.

"Don, you _threw_ a coffee mug across the room and smashed it against the wall for no reason." Leo said, nodding to the wall. I clenched my fists.

_Yeah, get mad Donatello. You NEED the needles. You NEED to figure out what's wrong. Don't listen to them._ Don said. I grit my teeth. I yanked as hard as I could against the chains.

"They're too tight!" I yelled to Don. Splinter stood from the bed and stepped back.

"Don, is there any other test you can do that doesn't include needles?" Leo asked, trying to calm me.

"NO!" I yelled, pulling harder.

"Calm down my son." Splinter said, reaching a hand towards me. I grit my teeth and kept pulling.

"I need to make this stop!" I screamed, closing my eyes tight.

_You're scaring your brother and father, Donatello._ Don told me. I opened my eyes to see him standing in between Leo and Splinter.

"GO AWAY!" I ordered, making my wrists hurt from all the pulling. Leo gave me a worried look.

"Calm down Donnie." He said.

_Yeah, calm down Donnie._ Don mocked.

"Shut up!" I yelled, collapsing to my bed since I was a little out of breath.

_No, I don't think I will. You have to ask nicely Donatello._ Don said, leaning back against the wall where the broken coffee mug was.

"P-please stop." I cried, tears starting to roll down my face, "Make it stop." I begged. Splinter walked over quietly.

"Donatello, what happened?" He asked quietly. I sniffled and started crying, holding my hands up to my face.

"H-him," I said weakly, pointing a hand towards the wall. Both Leo and Splinter looked over then back at me in confusion.

"My son, there is nothing there." He said, putting a hand on my shoulder. I shook my head, my hands still to my face.

"He's taunting me. He's right there. He won't go away." I said, looking at him with teary vision.

"Who?" Leo asked, looking over sensei's shoulder. I closed my eyes and groaned.

"HIM!" I yelled, pointing at Don. Splinter shook his head.

"Donnie, I think that the mutagen made you schizophrenic." Leo said, nervousness in his voice.

"Leo, I don't have some mental disease. He's right there." I said, not looking at him but instead at Don.

_You tell him Donnie. I am real._ Don said, walking over and leaning against Splinter, _Now stop crying and get the needles._ He said. I clenched my fists and threw a punch at him. I smiled when it hit him and he back away to the shadows.

"Donnie!" Leo yelled, pulling Splinter up for some reason.

"What?" I asked, now calming down since Don was gone.

"You just punched sensei!" Leo answered. I stared at him in confusion.

"No I didn't." I said.

"Donnie, yes you did."

"No I didn't, Leo!" I yelled, slamming my fist against the bed, "I would never punch sensei without reason!"

"Then why did you?!" Leo demanded as sensei left the room.

"I DIDN'T!" I screamed. Leo shook his head and reached for the door.

"Donnie, you need to rest. You need to clear your mind." He said, "That's an order." I took a deep breath through my nose.

"Fine." I said flatly. I laid down and rolled over.

I couldn't have hit sensei. Could I?

**Please review and tell me what you think! I'm always open for ideas on upcoming chapters you want me to put in or any ideas for other fanfics!**


	3. Chapter 3

Donnie's POV

_Donatello_. Came a voice. I sighed and sat up, rubbing my sleepy eyes.

"You can't let me sleep for just a little bit?" I muttered, looking around the room. I blinked and suddenly saw Leatherhead in front of me, "AH!" I screamed, pushing myself back against my headboard. He leaned forward, making us face-to-face. I turned my head away and closed my eyes, feeling his breathing on me. My breath got quick and I started getting scared.

"H-how are you here?" I asked, still not looking at him. A low growl rumbled from his throat and I held my breath, closing my eyes tight. I opened my eyes slightly to see his eyes being glazed over. I pulled my knees up to my chest and let out a little whimper.

Leatherhead roared and my ears rang. Before I could react, he grabbed my head and slammed it back against the wall. I hunched over, holding my head with both hands. I grit my teeth, the pain almost unbearable.

"L-leave me alone." I ordered weakly, looking up at him with only one eye open. He growled and grabbed my head again, yanking me up and throwing me down against my bed. I groaned, coughing and tasting a bit of blood.

"Help!" I yelled, though it came out sounding like a cough. I watched Leatherhead disappear into the darkness. The pain of my head and everything else caught up with me and I started crying. There was probably a bruise on my head and on my plastron, "H-help!" I called a little louder. My wrists hurt from the shackles and just wanted to get out of them.

"Donnie! What's wrong?" Leo yelled, rushing into the room followed by Mikey. I looked up, my body shaking.

"L-leatherhead." I said, hugging myself. Leo sat down on my bed.

"Donnie, you know Leatherhead is in another dimension, don't you?" He asked, putting his hand on my shoulder. I shook my head.

"H-he was right here. " I said, staring at the covers, "Get me out of this room!" I yelled suddenly, pulling against the chains. Leo pushed me back.

"Don," He said softly. I looked at him.

"Leo, please. I have to get out of this room!" I said, my breathing getting quick.

"Donnie, calm down." Mikey said, walking over. I looked at my little brother.

"I'm sorry." I said, stopping, "I-I just really need to get out of here." I said, looking around the room. I started hearing whispers of Don's voice and shrunk back towards the wall, "Unlock the chains!" I yelled, pulling again. A shadow started moving across the room and took shape of Don and Leatherhead.

"GET ME OUT OF HERE!" I screamed, trying to get up and get away. Mikey looked at me with concern. My eyes filled with tears again as Leatherhead and Don grinned at me, "Please?" I asked, holding my wrists out towards Leo. Leo hesitated, staring at my hands.

"Donnie, they're not real!" He tried to tell me. I bit my lip and looked from him to Leatherhead and Don.

"Please, Leo?!" I begged, starting to cry from fear. Leatherhead took a step forward and I yelled out, covering my face with my hands. Suddenly, I felt the cold metal move and then slip down from my hands. I jumped from my bed and rushed to the hallway. Once there, I ran to the opposite wall and collapsed against it with relief. Leo and Mikey soon emerged from my room.

"Close the door!" I yelled. Mikey jumped in surprise and quickly closed the door, "Thanks." I said, resting my head back against the concrete. Mikey and Leo exchanged a worried look.

"Donnie, you have to be careful out here." Leo said, helping me up. I gave him a confused look.

"Why? I'm perfectly fine." I told him with a little smile.

"Just remember that they're only hallucinations." He said, putting a hand on my shoulder.

"Leo, for the last time, I do not have a mental disease." I said, rolling my eyes and walking towards the living area.

"Donnie, you have to listen to me." Leo said, running up to me.

"Leo-" I complained with a groan.

"Donnie." Leo said sternly, "Just don't get so worked up, okay?" I nodded, wanting to defy him, but deciding against it. I nodded and walked into the living area, glancing back to my room to the see silhouette of Don at the door.

"You feeling better Don?" Raph asked once I entered. I smiled, sitting down across from him.

"Actually, I feel pretty good." I said with a huge smile. Raph smiled back and went back to his magazine.

Leo's POV

What the heck is wrong with Don? I wondered, sitting down near him. Right now he looked bipolar by how happy he was now compared to the pleading and crying earlier. Something was definitely up and only he'd be able to figure it out. Should I let him do some experiments while he's like this or risk waiting?

"H-hey, Donnie?" I asked hesitantly. He looked over with the same smile.

"Yeah, Leo?" He responded, leaning back.

"Well, seeing that you're feeling better, I think you can probably so some experiments to see what the mutagen did." I told him. He gave a little laugh.

"Oh, I don't need to now. I'm good." He said with a shrug. I stared at him in disbelief.

"At least make sure nothing happened." I suggested, coming out sounding like I was begging. He sighed and stood up.

"I guess it wouldn't hurt." He said, starting to the garage. I started following him, "Why are you coming?" He asked, turning around.

"I'll keep you company." I said with a soft smile.

"I'd like to do this alone Leo." He said sternly. My smile faded, great, he was about to snap again.

"Don-" I started, being interrupted.

"Donatello," Sensai chimed in, "let Leonardo accompany you." He said. Don let out a little sigh.

"Fine, come-on Leo." He said, walking into his lab.

"What's first?" I asked, pulling up a stool next to his desk.

"Blood sample." He said, reaching into a drawer for a needle. I rushed over and grabbed it from his grasp, "Hey!" He said.

"I-I'll get it for you." I said, holding it away. He rolled his eyes and stuck his arm out.

"Right here." He said, pointing to a spot on his arm. He sighed and leaned back against his desk while I stuck the needle in his arm. I almost had to look away because I don't feel comfortable sticking pointy objects into my brothers.

"Thanks." Don said, dabbing a tiny piece of gauze on his arm.

"Come on back into the living room." I told him, nodding towards the door. He sighed and stood.

Donnie's POV

"Coming, Leo." I said, with a groan. Geez, doesn't he trust me?

_No. No I don't, Donnie._ Leo's voice ran in my ears. I furrowed my brows and turned around, then went back to slowly following my brother.

"You okay Don?" Leo asked, stopping right before the door.

"Y-yeah." I answered after a little pause. Leo turned back to the door.

_You're going crazy, Don._ I heard Leo say again. I grabbed my older brothers arm and spun him around.

"What did you say?" I asked with a bit of anger and confusion.

"N-nothing." Leo answered with confusion. I let go and looked around the room again.

_Once you've lost your sanity, we're going to have to get rid of you, you know_. Leo said, an edge in his voice.

"What?!" I asked, grabbing Leo again.

"Don, let me go." Leo said, trying to squirm out of my grasp.

"What did you say?" I asked again sternly. He shook his head and gave me a weird look.

"Nothing." He answered.

_I said you're going crazy. You're going to have to be chained to that wall for now on. We can't have a crazy maniac running around the lair_. I heard him say with a little laugh. I stared at my brother. His mouth didn't move, but it was his voice.

"Are you hearing things again?" Leo asked, shaking my hand off. I glared at him, about to smack him.

"No!" I yelled, "I'm perfectly fine!" I yelled at him. He stared at me with the same look as when I was chained up.

"M-maybe you should go back to your r-" Leo started, taking a step towards me.

"NO!" I screamed, kicking him and retreating to my desk. He fell to the floor and stared at me in shock.

_You are so stupid_, Don. He said with a heavy sigh. I grit my teeth.

"Shut up, Leo!" I demanded. Leo looked at me.

"DONNIE! I AM SERIOUSLY DOING NOTHING!" He yelled, coming over and grabbing me by the shoulders.

_Nothing except telling you the hard, cold truth._ I heard. I looked away, _Look at me when I'm talking to you, Don_. He mocked. I shook my head.

"Donnie, what's wrong?" Leo asked, calming down. He let me go and I collapsed to the ground.

_Like I care what's wrong with you_. I slammed my fist as hard as I could onto the concrete floor over and over until it felt like my fist was broken.

"DONNIE! STOP!" Leo yelled, yanking me up by my arm.

_No, keep going. It's nice to see you get what you deserve._ I bit my lip and started crying.

"Donnie," Leo said, trying to get me to look at him.

_Go kill yourself._ I started crying hard, covering my face with my broken hand.

"G-go away." I said between sobs, "PLEASE?!" I screamed. Leo shook my shoulders again, " GO AWAY LEO!" I yelled at him, shooting up and punching him hard in the face. He staggered back and held his jaw. Tears blurred my vision as I walked over and kicked him in the gut. He fell to the ground, gasping for air.

"STOP!" He yelled, trying to catch his breath. I kicked him more.

"You go kill _yoursel_f." I spat, leaning down towards him. Leo gave me a shocked look.

"D-donnie," He coughed out. I gave one more kick in his head, knocking him out.

"Shut up." I told him coldly.


End file.
